How do I use the new curve fit function to fit me curve?

Hi, I am seriously struggling with this as im not a coder and do not dare aspire to be one but none the less I am trying to create a function from the variables ro3 and temp so I can then use that function to manipulate other variables I am yet to create. I was following the curve fitting for non-coders but I have gotten lost after creating a function to match my curve...

%Very Basic graph plot...
clc;                                                        %Clear 
temp=[-15,-10,-5,0,10,20];                                     %Defining Temp points -15deg C to 20deg C
ro3=[3300,790,300,138,99,72];                                  %defining Resistivity Ohm.m(sqrd)
%I previously used CurveFit function to define my function 'TempFit'
            %General model:
            %     cf(temp) = a*exp(-b*temp)+c
            %     Coefficients (with 95% confidence bounds):
            %       a =      0.1419
            %       b =      0.4218
            %       c =  -1.887e-15  (-26.78, 26.78
cf=NewTempFit(ro3,temp);                                       %load my Curve fit function 
temperature=logspace(-1,2,100);
r3=cf(temperature);                                            %Plot temp - ro3 as points only
plot(temperature,r3)
grid                                                        %display grid
title('Graph of Soil Resistivity with Temp and moisture content of %15 soil weight')   %Name of Graph
ylabel('Typical Resistivity (Ohm.m)')                                                   %Y axis label
xlabel('Temperture (Deg C)')                                                                %x axis label

here is my curve fit function

function [fitresult, gof] = createFit(temp, ro3)
%CREATEFIT(TEMP,RO3)
%  Create a fit.
%
%  Data for 'Ohm.m-Temp' fit:
%      X Input : temp
%      Y Output: ro3
%  Output:
%      fitresult : a fit object representing the fit.
%      gof : structure with goodness-of fit info.
%
%  See also FIT, CFIT, SFIT.

%  Auto-generated by MATLAB on 09-Sep-2018 09:51:12
%%Fit: 'Ohm.m-Temp'.
[xData, yData] = prepareCurveData( temp, ro3 );

% Set up fittype and options.
ft = fittype( 'a*exp(-b*temp)+c', 'independent', 'temp', 'dependent', 'ro3' );
opts = fitoptions( 'Method', 'NonlinearLeastSquares' );
opts.Display = 'Off';
opts.StartPoint = [0.141886338627215 0.421761282626275 0.915735525189067];

% Fit model to data.
[fitresult, gof] = fit( xData, yData, ft, opts );

% Plot fit with data.
figure( 'Name', 'Ohm.m-Temp' );
h = plot( fitresult, xData, yData );
legend( h, 'ro3 vs. temp', 'Ohm.m-Temp', 'Location', 'NorthEast' );
% Label axes
xlabel temp
ylabel ro3
grid on

For whatever reason I cannot get this functions to impose itself on the values when i plot them. Any assistance would be much appreciated.

[Astha Singh]

Hi Matthew,

I understand that you have already written the function 'NewTempFit' and now facing an error while using the same to get a plot.

To understand where you are facing the error, can you please define the 'NewTempFit' function that you are using in your code?